Flexible circuits are widely used in the electrical arts to make electrical connections between separate pieces of hardware. Such circuits are generally made from an electrically inert substrate such as polyester film upon which are printed electrically conductive traces. The traces are printed with conductive inks containing copper, silver, gold, carbon or any electrically conductive material, generally in an epoxy base. The cost of using flexible circuits depends on the distance and shape between the circuits to be connected. Flexible circuits are made using polyester film substrates of a fixed width and length. The circuits are patterned onto the substrate in the most efficient manner possible to reduce waste. Circuits that require turns or very long segments of straight lengths often waste significant material due to limitations on how the patterns can be laid out to maximize the use of material.
Using current technology, substrate waste can be reduced by using hard connectors between discrete sections of flexible circuits. While such approach reduces the amount of substrate used, using hard connectors between discrete sections of circuits adds cost and complexity.
There is a need in the electrical arts for a means to join printed circuits including both flexible and relatively inflexible circuits without a need for hard connectors.
Additionally, there is a need in the art for connections between printed circuits which can be moved to permit different configurations of the circuit. This need frequently arises when the electrical components to be connected need to be placed at varying distances from each other based on the needs of the user.
There is a specific application for the present technology in the medical field where patients are monitored via electrodes placed on the skin. Electrodes or other electrical sensing equipment have long been used in the medical field for attachment to a human being or otherwise living organism in order to monitor physiological functions such as the electrical signals of the heart. The electrodes take on several forms and must in some way be electrically connected to a device suitable for storing and oftentimes, for processing and analyzing the electrical signals gathered from the sensing equipment.
Typically, individual electrodes are connected to the monitoring device by separate electrical leads. A flat sheet, tab-like electrode is often connected to the lead wire using an alligator-type clip formed by two jaws which clamp together to secure the lead wire to the electrode. The jaws often contain various mechanisms for crimping the electrode surface for better connection. However, such a configuration restrictively grips the electrode thereby preventing any movement between the lead wire and the electrode. Such a limitation leads to significant cable strain along the lead wire and the need to disengage and reattach the lead wires whenever the subject being monitored moves or the monitoring equipment is moved in a different orientation. Described are several connections to tab-like electrodes which provide for some rotational movement between the electrode and lead wire. For example, the electrode can include a hole whereby a protruding member located on the surface of one of the jaws of the alligator clip is inserted through the hole and when the two jaws are clamped together, structurally mates with the opposite jaw. Therefore, the electrode is not restrictively gripped in place but rather can be rotated around the protruding member.
Where stud-type electrodes are used, typically an individual lead wire is connected to the stud portion of the electrode using an alligator-type clip or a snap-type connector whereby the stud portion is inserted into a tight aperture formed in the connector such that the stud is snapped into connection. Both of these configurations ordinarily only serve to connect a single lead wire to an electrode and therefore require that each electrode be individually connected to a monitoring device. Many applications require that more than one electrode be used in sensing a physiological function and often, it is not practical to require each electrode be individually connected. The use of individual leads risks entanglement and confusion between the wires. Although a connector which may be rotated with respect to the electrode is much more easily adapted to the shape of a stud-type electrode in comparison to a tab-style electrode, the use of a plurality of individual wires to attach a subject to a monitoring device severely limits the mobility of the subject being monitored. The comfort of the subject is compromised and the ability to monitor a physiological function while the subject is active is nearly impossible.
Chest assemblies have been disclosed whereby a plurality of electrode connections or electrodes are integrated into a single, flexible chest patch. The electrode connections are typically in the form of slots or holes integrated into the surface of the chest patch such that the slots or holes are snap-fitted onto the protruding member of stud-type electrodes. The electrical pathways leading away from the electrode connections are typically circuit traces printed along the patch substrate which terminate at a single terminal on an edge of the patch such that the traces are in close proximity to one another. Various means are used to connect the terminal edge to a monitoring device using a single connection. Therefore, a plurality of individually connected electrode leads is eliminated. However, a single wire connection between the terminal edge and the monitoring device still requires that the subject be tethered such that mobility and comfort are still restricted. Also, due to the fact that the electrode connections are integrated along a single chest patch, the placement of the electrodes upon the subject being monitored is fixed or substantially limited in order to correspond to the electrode connections defined in the chest patch. Therefore, only one configuration is possible. Although limiting electrode placement may be beneficial in avoiding improper placement, the benefit is limited as the chest patch must still be properly placed on the chest in the first instance. Also, the chest patches are ordinarily composed of a flexible material such as a plastic derivative in order for the patch to conform well to the variable surface of the chest for a good connection. Therefore, the chest patch must be packaged assembled in its entirety and great care must be taken so that the patch is not bent or otherwise problematically shaped as it is easily pliable.
Other chest assemblies with integrated electrode connections have eliminated the use of a single wire connection to a separate monitoring device and replaced it with data processing means that are integrated into the chest patch. The chest patch is either made completely self-sufficient or has an antenna included for wireless transmission to a separate monitoring device. Although such a configuration provides much greater comfort and mobility to the subject being monitored, the costs of such an integrated chest patch are much higher and thus would not be disposable. Where the chest assemblies will have a high frequency of use, a disposable component is much more desirable than a costly device which needs to be cleaned after each use.
These as well as other novel advantages, details, embodiments, features, and objects of the present invention will be apparent to those skilled in the art from the following detailed description of the invention, the attached claims and accompanying drawings, listed herein below which are useful in explaining the invention.
It is an object of this invention to provide a simple, easily connected and disconnected electrical connector which can be used to connect one or more flexible, printed circuit traces originating from separate electronic devices to a stud-type electrode. Such a connection may then be used as an integrated electrode connector in a chest assembly whereby the flexible, printed circuit traces originate from other integrated electrode connections along the length of the chest assembly. Therefore individual, multiple lead wire connections to the electrodes are eliminated and the comfort and mobility of the subject being monitored is maintained. One or more printed circuit traces terminate onto flexible circuit ends that each contain a centering axis whereby an aperture is formed. The ends of the circuit traces form an annular shape that is concentric to the center aperture. The connector consists of a top and bottom part, either separated or connected by a single living hinge, both containing a centering axis whereby an aperture is formed. The top and bottom parts are constructed so as to have a mating mechanism along the circumference of the inner aperture and/or along their outer edges such that they may be snap-fitted into connection with one another. The circuit ends are overlapped upon one another such that the printed circuit traces on each circuit end are in direct face-to-face electrical contact with one another. The center apertures of the stacked circuits are aligned with the center apertures of the top and bottom parts such that when the top and bottom parts are snap-fitted together, the stacked circuits are secured between the two parts. The snap-fit is easily connected and disconnected thereby reducing the chest assembly to multiple modular parts which are more easily manufactured and packaged in comparison to one unit. The protruding member of a stud-type electrode is inserted through the center aperture of the connector so as to electrically connect the printed circuit traces to the electrode.
It is a further object of this invention to provide a simple electrical connector that can be used to connect one or more flexible, printed circuit traces originating from separate electronic devices to a stud-type electrode such that each connected circuit may rotate freely about its centering axis and still maintain electrical contact with the overlapping circuits and the electrode. The ability to adjust the flexible circuits angularly with respect to one another allows for freedom of movement and placement of the electrode connections upon the chest that could not be achieved where the electrode connections are fixed in place on a single chest patch. Although the circuit ends are pressed into overlapping contact between the two flat, top and bottom surfaces of the connector and are held in place by a snap-fit mating mechanism at the aperture running through the centering axis of the connector, the circuits are not pressed so tightly together that they cannot be rotated easily. Also, although the circuit ends are held in place by a snap-fit mating mechanism at their centering axis, this snap-fit only serves to connect the top and bottom surfaces of the connector and to align the centering axes of the connector body and the circuit ends without restricting the rotation of the circuit ends.
It is a further object of this invention to provide a means for switching the connector between an “On” and “Off” position. The length of the annular printed circuit traces may be varied such that there are areas of angular rotation at which the annular traces of the overlapping circuits are no longer overlapping and therefore, are no longer in electrical connection placing the connector into an “Off” position.
It is a further object of this invention to provide several means for limiting the rotational movement about the centering axis of the circuit ends in applications where such a restriction provides an advantage. For example, the snap-fit mechanism that connects the top and bottom surfaces of the connector may be placed at the outer edge of the surfaces, either along the entire edge or intermittently, so as to prevent the circuit ends from traversing a complete rotational path about the circumference of the connector body. Also, a second hole may be incorporated into the connector such that insertion of a pin into the hole restricts the rotation of the circuit ends.
It is a further object of this invention that the described electrical connector be disposable.